The invention relates to a computer aided design (CAD) system and, more particularly, to a distributed data CAD system suitable for design of an assembled part whose data is distributed.
In the conventional CAD system, a plurality of terminals are connected to a single host computer by a network and data of the parts (an assembly constructed by a plurality of parts is also called a part here) is concentratedly managed by the single host computer.
To handle a number of parts having a complicated construction, parts data is divided into construction information (indicative of the parent/child relation among the parts) and the shape information (indicative of a drawing of the parts) and stored into a parts construction file and a parts shape file, respectively. A construction of assembly is shown by, for instance, a tree structure by using the construction information.
According to a processing procedure of the conventional CAD system, the parts number of the part to be referred is supplied from a certain terminal and transmitted to the host computer. The host computer searches the parts construction file by using the received parts number as a key, thereby obtaining the construction information of such a part. The construction information has the parts number, the shape name, and the parts number of the child part. When there is a child part among the searched parts, the child part is regarded as a part and the parts construction file is searched by using the parts number of such a child part as a key, thereby obtaining the construction information of the child part. The above processes are repeated until the child part doesn't exist. When the construction information of all of the parts constructing the part are obtained, the construction information is transmitted to the terminal. The terminal which has received the construction information searches the shape names of all of the part constructing an assembled part and transmits the shape names to the host computer. The single parts shape file has the shape name and the shape information. The host computer which has received the shape names searches the single parts shape file by using the shape names as a key and transmits the shape information of all of the parts to the terminal. The terminal which has received the shape information forms display data and displays it on a display.
There is also a system such that work stations (hereinafter, referred to as WSs) to concentratedly manage parts data are connected by a network and a file which is possessed by another WS can be commonly used.
In this case, all of the construction information of the parts which should be designed by the user and the parts shapes corresponding to those parts have been stored in the file connected to its own WS. Each user generally executes processes by using only the user's own WS.
In the case where there is a restricted relation between the parts to be designed by the user himself and the parts to be designed by another user and the user must refer to the parts in charge of another user upon designing of the parts in charge of the user, since the data of such parts doesn't exist in the file of the user's own WS, the user communicates with the WS having the file in which the data of such parts has been stored and declares a common use and switches the file, thereby using the target data as if such data existed in the file connected to the user's own WS. In the above case, however, the user must preliminarily know the location of the file of another user whose common use should be declared.
As literatures regarding such a kind of technique, for instance, there are JP-A-62-128365 and JP-A-2-171860.
In the above conventional technique, no consideration is paid to a point that a number of related parts data are distributively managed. The host computer or each terminal concentratedly manages those parts data, so that there are problems such as deterioration of a response speed, limitation of the machine performance, limitation of resources, and the like.